929
CORRESPONDENCE
Tube (mm) 11.0 9.5, 10 and 10.5
Length (mm) 250 230 220 210
9.0 8.5
Smaller diameter tubes are manufactured in proportion. To avoid damage to the inflating tube by the endotracheal connector, the tubes supplied to us had to be cut at least 10-15 mm longer than the above lengths. If the tubes were cut immediately above the take-off point, there was a very high incidence of cuff failure. Because of our concern about this matter, we have measured the total lengths of tubes currently in use in this hospital. The following were the average total lengths for larger diameter tubes: Tube (mm)
Length (mm)
9.5 9.0 8.5
226 224 195
It is emphasized that these are average lengths and therefore the majority of tubes were cut considerably shorter than would have been possible with the new standard tubes. We do not think our practice is different from that in other British hospitals and we feel that this problem may concern many anaesthetists. We would suggest that those who have not yet used them should cut some of the existing tubes in accordance with the new standard and try these in clinical use, especially in patients of short stature. If they agree with us, and we feel that many will do so, they should make their feelings known. Otherwise the specialty may be faced with using tubes which are, in many cases, totally unsuitable. It is fair to add that the draft I.S.O. standard includes the following clause: "If the inflating tube be attached externally to the tracheal tube between the cuff and point of separation, the attachment shall be in such a manner that the inflating tube may be partly stripped off the tracheal tube, if required." It would appear from this, that many of us who have come to prefer the use of plastic tubes and tubes with inflating tubes incorporated into the parent tube wall may require to revert to the use of red rubber tubes. This, many of us feel, is undesirable.
We would urge any anesthetist who is asked to comment on the new standard specification not to do so without first using the new tubes. J. P. VANCE AND 1 1 OTHERS
Glasgow ALBUMIN EXTRAVASATION DURING SURGERY
Sir,—I have been interested in Dr Grogono's investigations into the relative losses of whole blood and albumin during anaesthesia and surgery (Grogono, 1976). If the small bowel is enclosed in an "Aldon" plastic intestinal bag during major abdominal surgery, as is now commonly practised, it is found invariably at the end of an operation that straw-coloured fluid has collected in the bag. The quantity of fluid depends on the duration of the procedure and on other variables, but in our patients the volume is usually approximately 150 ml. Analysis of the fluid has shown that the electrolyte and protein content closely resemble that of blood. When the small bowel is not enclosed during a long abdominal operation this transudate, together with that from other peritoneal surfaces, is lost on swabs and by suction. The summary of Dr Grogono's work does not give enough information to indicate if this is a full explanation of his findings, but it may well account for at least part, particularly as he did not observe this relative loss of protein during operations on the middle ear (Grogono, 1974). D. ZUCK
Enfield, Middlesex REFERENCES
Grogono, A. W. (1974). The assessment of albumin extravasation during surgery. Br. J. Anaesth., 46, 320. (1976). Methods of evaluating the extravasation of albumin during surgery. Br. J. Anaesth., 48, 266. Sir,—Thank you for allowing me to add a comment to Dr Zuck's letter. Albumin accumulation in the peritoneum has been described previously. Jarnum (1961) observed a loss into the peritoneum equivalent to 600 ml plasma at the end of a 3-h gastrectomy. Increased capillary permeability is characteristic of the inflammatory response and surgical trauma appears to be no exception. A fuller account of the work to which Dr Zuck refers is in preparation, but in summary, using isotope-labelled albumin and red cells, it has been found that during abdominal surgery there was a depletion of intravascular albumin by approximately 5% per hour. In addition there was an increase in capillary permeability by twofold or more, and there was a reduction in plasma volume which exceeded that attributable to blood loss. These findings are explicable on the basis of the inflammatory response and the accumulation of protein in the peritoneal cavity may be viewed as part of this process. However, peritoneal accumulation is not the only situation in which albumin extravasation occurs. Skillman (1976) confirms that loss occurs into other traumatized areas such as skin and muscle; and in the patients I studied, there were six episodes of albumin extravasation unrelated to trauma, but apparently related to stress (such as pain experienced during emergence from anaesthesia and dis-
Downloaded from http://bja.oxfordjournals.org/ at New York University on June 29, 2015
new tubes, made to the new standard, arrived from our supplier. One aspect of the new design of cuffed tubes which concerns us is the point of separation of the cuff inflating tube from the parent tube wall. It is now proposed that this should be much further from the bevelled end of the tube than previously and it is now to be so high on the tube that, in many patients, several centimetres of the tube will require to protrude from the mouth to avoid intubating a bronchus. This is unsatisfactory in any anaesthetic situation, but in anaesthesia for surgery of the head and neck it is potentially dangerous, since such a tube may kink from the pressure of drapes and the surgeon's hands. There is the additional inconvenience in respect of access to the operating field in nasal and facial procedures. The recommended new lengths from bevel tip to separation point for the larger diameter tubes are as follows:
CORRESPONDENCE
Tube (mm) 11.0 9.5, 10 and 10.5
Length (mm) 250 230 220 210
9.0 8.5
Smaller diameter tubes are manufactured in proportion. To avoid damage to the inflating tube by the endotracheal connector, the tubes supplied to us had to be cut at least 10-15 mm longer than the above lengths. If the tubes were cut immediately above the take-off point, there was a very high incidence of cuff failure. Because of our concern about this matter, we have measured the total lengths of tubes currently in use in this hospital. The following were the average total lengths for larger diameter tubes: Tube (mm)
Length (mm)
9.5 9.0 8.5
226 224 195
It is emphasized that these are average lengths and therefore the majority of tubes were cut considerably shorter than would have been possible with the new standard tubes. We do not think our practice is different from that in other British hospitals and we feel that this problem may concern many anaesthetists. We would suggest that those who have not yet used them should cut some of the existing tubes in accordance with the new standard and try these in clinical use, especially in patients of short stature. If they agree with us, and we feel that many will do so, they should make their feelings known. Otherwise the specialty may be faced with using tubes which are, in many cases, totally unsuitable. It is fair to add that the draft I.S.O. standard includes the following clause: "If the inflating tube be attached externally to the tracheal tube between the cuff and point of separation, the attachment shall be in such a manner that the inflating tube may be partly stripped off the tracheal tube, if required." It would appear from this, that many of us who have come to prefer the use of plastic tubes and tubes with inflating tubes incorporated into the parent tube wall may require to revert to the use of red rubber tubes. This, many of us feel, is undesirable.
We would urge any anesthetist who is asked to comment on the new standard specification not to do so without first using the new tubes. J. P. VANCE AND 1 1 OTHERS
Glasgow ALBUMIN EXTRAVASATION DURING SURGERY
Sir,—I have been interested in Dr Grogono's investigations into the relative losses of whole blood and albumin during anaesthesia and surgery (Grogono, 1976). If the small bowel is enclosed in an "Aldon" plastic intestinal bag during major abdominal surgery, as is now commonly practised, it is found invariably at the end of an operation that straw-coloured fluid has collected in the bag. The quantity of fluid depends on the duration of the procedure and on other variables, but in our patients the volume is usually approximately 150 ml. Analysis of the fluid has shown that the electrolyte and protein content closely resemble that of blood. When the small bowel is not enclosed during a long abdominal operation this transudate, together with that from other peritoneal surfaces, is lost on swabs and by suction. The summary of Dr Grogono's work does not give enough information to indicate if this is a full explanation of his findings, but it may well account for at least part, particularly as he did not observe this relative loss of protein during operations on the middle ear (Grogono, 1974). D. ZUCK
Enfield, Middlesex REFERENCES
Grogono, A. W. (1974). The assessment of albumin extravasation during surgery. Br. J. Anaesth., 46, 320. (1976). Methods of evaluating the extravasation of albumin during surgery. Br. J. Anaesth., 48, 266. Sir,—Thank you for allowing me to add a comment to Dr Zuck's letter. Albumin accumulation in the peritoneum has been described previously. Jarnum (1961) observed a loss into the peritoneum equivalent to 600 ml plasma at the end of a 3-h gastrectomy. Increased capillary permeability is characteristic of the inflammatory response and surgical trauma appears to be no exception. A fuller account of the work to which Dr Zuck refers is in preparation, but in summary, using isotope-labelled albumin and red cells, it has been found that during abdominal surgery there was a depletion of intravascular albumin by approximately 5% per hour. In addition there was an increase in capillary permeability by twofold or more, and there was a reduction in plasma volume which exceeded that attributable to blood loss. These findings are explicable on the basis of the inflammatory response and the accumulation of protein in the peritoneal cavity may be viewed as part of this process. However, peritoneal accumulation is not the only situation in which albumin extravasation occurs. Skillman (1976) confirms that loss occurs into other traumatized areas such as skin and muscle; and in the patients I studied, there were six episodes of albumin extravasation unrelated to trauma, but apparently related to stress (such as pain experienced during emergence from anaesthesia and dis-
Downloaded from http://bja.oxfordjournals.org/ at New York University on June 29, 2015
new tubes, made to the new standard, arrived from our supplier. One aspect of the new design of cuffed tubes which concerns us is the point of separation of the cuff inflating tube from the parent tube wall. It is now proposed that this should be much further from the bevelled end of the tube than previously and it is now to be so high on the tube that, in many patients, several centimetres of the tube will require to protrude from the mouth to avoid intubating a bronchus. This is unsatisfactory in any anaesthetic situation, but in anaesthesia for surgery of the head and neck it is potentially dangerous, since such a tube may kink from the pressure of drapes and the surgeon's hands. There is the additional inconvenience in respect of access to the operating field in nasal and facial procedures. The recommended new lengths from bevel tip to separation point for the larger diameter tubes are as follows:
